For years, a certain type of power package--having synthetic resin (plastic) surrounding a mounting hole--has been popular for electronic components such as power semiconductors and power resistors. Examples include the Motorola "Full Pak" power semiconductors and Caddock MP816, MP850, and MP930 power resistors. In this type of package, the active element and its support structure are often located in close heat-dissipating relationship to the bottom (mounting surface) of the device and thus to an external heatsink on which the device is mounted. Mounting to the external heatsink is typically effected by a single bolt (screw).
There is always a need for increased power ratings in electronic or electrical devices, especially where the increased power ratings may be achieved at substantially no cost. Accordingly, it would be a distinct benefit to the industry if power resistor devices of the type indicated could--at little or no cost--be so constructed as to have higher power ratings.